Strictly speaking, it is on its own island: Artillery Island [ru] (Kronverksky Island), which is separated from the rest of Petrogradsky Island by the Kronverksky Canal [ru].
On 13 July 1826, five participants of the Decembrists' conspiracy were hanged on the eastern rampart of the Kronverk (in 1975, an obelisk was installed on the supposed site of execution).[1]